The present invention relates to an image printing apparatus and method using a printing head having a K (black) nozzle array and color nozzle array, which are shifted in the sub-scanning direction and, more particularly, to an image printing apparatus and method which prevent ink smearing generated when K (black) ink and color ink are discharged to land on the same landing point, and a storage medium.
As an information output apparatus in, e.g., a wordprocessor, personal computer, or facsimile apparatus, a printer for printing desired information such as characters or images on a sheet-shaped printing medium such as a paper sheet or film is used.
Various printing schemes are known as the printing scheme of a printer. In recent years, an ink-jet scheme has particularly received a great deal attention because noncontact printing on a printing medium such as a paper sheet is possible, color printing is easy, and it is silent. As its construction, a serial printing scheme is generally widely used because it is inexpensive and allows easy size reduction. This scheme prints by attaching a printing head for discharging ink in accordance with desired print information and reciprocally scanning the printing head in a direction perpendicular to the feeding direction of a printing medium such as a paper sheet.
Conventionally, in an image printing apparatus using a printing head in which K (black) nozzles and color nozzles are shifted in the sub-scanning direction (printing paper conveyance direction), print data transferred for each raster must be temporarily stored in a drawing (writing) buffer and continuously stored until printing corresponding to each nozzle is done.
For example, for a printing head constructed by K (black) and color nozzles (C1 (dark cyan), C2 (light cyan), M1 (dark magenta), M2 (light magenta), Y1 (dark yellow), and Y2 (light yellow)) comprising 128 nozzles for each color, normally, the color nozzles are shifted from the K (black) nozzles by (the number of K (black) nozzles +xcex1) or more so as not to print any color in the next pass after printing K (black).
Here, the value xcex1 depends on the management amount of a divided printing buffer. If the printing buffer is managed in blocks of 16 bits, the shift amount further increases by 16 rasters, so the total shift amount is 128+16=144 rasters. When data transferred for each raster is received, printing is executed while checking whether smearing can occur at the same landing position.
However, the print data is transferred for each raster. For this reason, to draw raster data for the first K (black) nozzle, data corresponding to (128+16 +128) rasters must be prepared for each color nozzle from the 128th nozzle of the head. This requires a large RAM capacity.
In another scheme, data corresponding to only a printing portion of the head having a shift in advance is transferred to reduce the RAM capacity. In this scheme, it cannot be checked whether data is present at the same landing position because data on the same raster is not transferred. As a result, if data is present at the same landing position, smearing occurs in printing by the K (black) nozzles and color nozzles.
The present invention has been made to solve the problems of the prior art, and has as its object to provide an image printing apparatus and method capable of preventing any smearing that occurs in printing at the same landing position using nozzles of different colors with a smaller RAM capacity.
In order to achieve the above object, an image printing apparatus according to an aspect of the present invention has the following arrangement. The image printing apparatus which causes a carriage having, for each of a plurality of inks, a printing head having a plurality of printing elements arrayed in a predetermined direction to scan on a printing medium in a direction perpendicular to the array direction of the printing elements, thereby forming a color image on the printing medium, comprising a reception buffer for storing print data transmitted in a raster format, printing buffers for divisionally storing the data stored in the reception buffer for each ink and for each predetermined area to be printed by the printing head, determination means for determining whether a designated printing buffer and an undesignated printing buffer in the printing buffers have data to be printed at the same position, and preventing means for, when it is determined that the data to be printed at the same position are present, preventing any ink smearing that occurs in printing at the same position.
For example, the plurality of divided printing buffers have information of different inks to form the color image and information of a distance between the inks.
For example, the designated printing buffer comprises printing buffers for a plurality of kinds of ink.
For example, the designated printing buffer comprises a printing buffer for K (black) ink and printing buffers for inks other than the K (black) ink.
For example, the determination means compares data representing whether each position is to be printed, which are stored in the designated printing buffer and the printing buffers other than the designated printing buffer, and when the data to be printed at the same position are present, sets a flag indicating that the data indicate the same position.
For example, the preventing means prevents the ink smearing by changing a timing of printing using each ink.
For example, the preventing means prevents the ink smearing by changing a timing of printing in continuously printing using ink other than the K (black) ink at the same position where printing has been executed using the K (black) ink of the inks.
For example, the printing head comprises an ink-jet printing head which prints by discharging ink.
For example, the printing head comprises a printing head which discharges ink using a thermal energy and has a thermal energy transducer for generating thermal energy to be applied to the ink.
In order to achieve the above object, an image printing method according to another aspect of the present invention has the following arrangement. An image printing method using an image printing apparatus which causes a carriage having, for each of a plurality of inks, a printing head having a plurality of printing elements arrayed in a predetermined direction to scan on a printing medium in a direction perpendicular to the array direction of the printing elements, thereby forming a color image on the printing medium, the image printing apparatus comprises a reception buffer for storing print data transmitted in a raster format, and printing buffers for divisionally storing the data stored in the reception buffer for each ink and for each predetermined area to be printed by the printing head, and the method comprises the determination step of determining whether a designated printing buffer and an undesignated printing buffer in the printing buffers have data to be printed at the same position, and the preventing step of, when it is determined that the data to be printed at the same position are present, preventing any ink smearing that occurs in printing at the same position.
In order to achieve the above object, a computer-readable storage medium according to still another aspect of the present invention has the following arrangement. A control program which controls an image printing method using an image printing apparatus which causes a carriage having, for each of a plurality of inks, a printing head having a plurality of printing elements arrayed in a predetermined direction to scan on a printing medium in a direction perpendicular to the array direction of the printing elements, thereby forming a color image on the printing medium, the image printing apparatus comprises: a reception buffer for storing print data transmitted in a raster format; and printing buffers for divisionally storing the data stored in the reception buffer for each ink and for each predetermined area to be printed by the printing head; and the control method comprises: a code of the determination step of determining whether a designated printing buffer and an undesignated printing buffer in the printing buffers have data to be printed at the same position; and a code of the preventing step of, when it is determined that the data to be printed at the same position are present, preventing any ink smearing that occurs in printing at the same position.
In order to achieve the above object, a computer-readable storage medium according to still another aspect of the present invention has the following arrangement. A computer-readable storage medium storing a control program which controls an image printing method using an image printing apparatus which causes a carriage having, for each of a plurality of inks, a printing head having a plurality of printing elements arrayed in a predetermined direction to scan on a printing medium in a direction perpendicular to the array direction of the printing elements, thereby forming a color image on the printing medium, the image printing apparatus comprises: a reception buffer for storing print data transmitted in a raster format; and printing buffers for divisionally storing the data stored in the reception buffer for each ink and for each predetermined area to be printed by the printing head; and the control method comprises: a code of the determination step of determining whether a designated printing buffer and an undesignated printing buffer in the printing buffers have data to be printed at the same position; and a code of the preventing step of, when it is determined that the data to be printed at the same position are present, preventing any ink smearing that occurs in printing at the same position.
Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof.